Coiled tubing level wind system

ABSTRACT

The level winding system described has a storage reel, a knuckle boom and a roller guide head for control the winding and unwinding of coiled tubing from the storage reel. The knuckle boom has a crane attached to a rotatable, elevatable, and extendible boom with an attached roller guide head. The described level winding system is easy to control, robust, very adaptable to different rig geometries and tubing sizes, and easy to maintain.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application, pursuant to 35 U.S.C. 111(b), claims the benefit of the earlier filing date of provisional application Serial No. 60/303,184 filed Jul. 5, 2001, and entitled “Coiled Tubing Level Wind System.”

FIELD OF THE INVENTION

[0002] The present invention relates to the level winding on a reel of coiled tubing for use in drilling, production, and servicing of wells used for production of petroleum products. The invention is used to ensure that the tubing is stored on the reel in a manner, which will cause it to lie on the reel in a compact pattern and unspool without risk of binding.

BACKGROUND OF THE INVENTION

[0003] When continuous coiled tubing is to be used in a well as a service tubing string, a production string, or a drill string, it must be taken from a reel, forced into the well, manipulated, withdrawn from the well, and stored back on its reel. Tractive means, commonly termed coiled tubing injectors, are used to force the tubing into or out of the wellhead. The tubing is generally under relatively low tension between the tractive means and the storage reel. When the tubing is respooled onto a reel located close to the tractive means, level winding is essential to ensure that the tubing will load densely onto the reel. Additionally, level winding prevents unstable local stack-ups of tubing, which can result in binding of the tubing when it is pulled from the reel. Lastly, level winding minimizes the tendency to overstress and dent or kink tubing where it crosses a lower layer of tubing at a large angle.

[0004] To date, four basic types of level winding schemes have been used for coiled tubing. The first and most common type utilizes a ball reverser or similar pawl-type reverser which has a shaft with two intersecting coaxial grooves, one being right-handed and the other being left-handed, cojoined at both opposed travel limits by turnaround sections. A swiveling tracking pawl or a special ball nut constrained to follow a separate linear track parallel to and offset from the shaft axis is used as a follower to follow the path of the rotating shaft. See for example the 1997 Flennor Division of Norco, Inc. Catalog “Ball Reverser”. A tubing guide, typically with rollers constraining the tubing on three or four sides, is mounted to the follower to compel the tubing to follow the track of the follower. While the reverser shaft is rotated in a fixed ratio to the turns of the drum, the nut or tracking pawl is caused to reciprocate on its linear track. The turnarounds for the reverser are typically located slightly inside of the flanges of the take-up reel. This type of system is offered by Hydrarig, Inc. of Fort Worth, Tex. and others. In some cases, an independently controlled hydraulic cylinder is used to displace the tubing guide relative to the follower so that control of the winding can be varied as necessary with the different tubing sizes and attendant bending stiffness variations. Level wind systems using reversers are generally expensive and easily damaged. Additionally, because they are directly driven, the drive ratio between the reel and the reverser shaft must be changed for each size of tubing, which is used on the reel.

[0005] A second type of level winding system for coiled tubing rigs is shown in Gipson U.S. Pat. No. 4,673,035 and used by Precision Drilling, Inc. of Brady, Tex. For this system, the entire reel is reciprocated by means of one or more hydraulic cylinders in the direction of the rotational axis of the reel to effect level winding.

[0006] A third type of reciprocating device, offered by Amacoil, Inc. of Aston, Pa. is used for certain level winds outside of the coiled tubing industry. This device utilizes rings mounted in a linearly reciprocable follower, which bear on and are rotated by a smooth cylindrical shaft. The Model RG, shown in the “Amacoil/Uhing Linear Actuators” 2001 Catalog, rotates the shaft in a manner similar to that used by ball reversers. Means is provided for controlling the pitch for the device by altering the axial orientation of the follower rollers relative to the smooth shaft axis. A reverser mechanism triggered by abutment contact at either end of the travel is provided with the Model RG reciprocator. While this device might be satisfactory for the smallest sizes of coiled tubing, the forces deliverable by the device appear to be insufficient for use with the largest sizes of coiled tubing. Additionally, the pitch of the rings must be very carefully set in order to obtain accurate reciprocation whenever the tubing size is changed.

[0007] A fourth type of level wind device uses guide rollers reciprocated by either a hydraulic cylinder or a screw/nut combination driven by a rotary motor. Alternately, a linear electric motor could be used for cases when only limited forces are required. Several types of variants of this type of device have been developed for use with pipe reel barges and for other level wind applications. The earliest systems utilized direct manual control of the reciprocation. Direct mechanical control of switches or hydraulic valves was used for older automatic systems to reverse the direction of the traveler. Newer systems can use preprogrammed electronic controls either with or without feedback sensors. These systems require separate support structures, protection from mechanical damage, and for electronic systems, protection from lightning damage.

[0008] Thus, a need exists for a simpler level winding system with enhanced flexibility to permit it to better control the winding for large ranges of reel core diameters and outer diameters and tubing sizes.

SUMMARY OF THE INVENTION

[0009] The invention contemplates improved flexibility of the level winding system to permit it to better control the winding for large ranges of reel core diameters and outer diameters and tubing sizes. The present invention avoids some of the disadvantages of the level wind means discussed above by adapting an inexpensive small crane included with the coiled tubing rig to serve as a level wind device. This new means is easy to control, robust, very adaptable to different rig geometries and tubing sizes, and easy to maintain.

[0010] One aspect of the invention is a level winding rotationally mounted and axially extensible knuckle boom for use with a coiled tubing injector, the knuckle boom comprising (a) slewing means for controllably slewing about a vertical axis; (b) elevating means for controllably elevating and lowering the boom; (c) extension means for controllably extending and retracting the boom; and (d) guide roller means for guiding a tubing during the tubing winding or unwinding onto or off of a storage reel, said guide roller means mounted on an outer end of said boom; whereby the boom is selectably controlled so that the tubing alignment is controlled by the roller guide means as the tubing is wound or unwound onto or off of the storage reel.

[0011] Another aspect of the present invention is A level winding system for use with a coiled tubing injector unit comprising (a) a tubing storage reel; (b) a crane having a boom, said crane comprising a rotating element for controllably rotating the boom about a vertical axis, a hydraulic cylinder for controllably elevating and lowering the boom, and an extension element for controllably extending and retracting the boom; and (c) a guide roller element for guiding a tubing during the tubing winding or unwinding onto or off of the tubing storage reel, said guide roller element mounted on an outer end of said boom and comprising a roller bracket, a horizontal roller and an opposed pair of substantially parallel orthogonal rollers, wherein the axes of the orthogonal rollers are substantially perpendicular to the axis of the horizontal roller; whereby the roller guide element is positioned by the crane and the boom as the roller guide element guides the tubing onto or off of the storage reel.

[0012] Yet another aspect of the present invention is a level winding system comprising a reel holding a coiled tubing, said tubing wound and unwound from the reel by the level winding system; a roller guide head proximal to the reel and comprising multiple rollers, said rollers partially or fully surround the tubing to partially constrain the lateral movement of the tubing; and roller guide head manipulation element comprising a crane, a plurality of crane actuators and a crane control device.

[0013] The foregoing has outlined rather broadly several aspects of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed might be readily utilized as a basis for modifying or redesigning the structures for carrying out the same purposes as the invention. It should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The novel features which are believed to be characteristic of the invention, both as to its organization and methods of operation, together with the objects and advantages thereof, will be better understood from the following description taken in conjunction with the accompanying drawings, wherein:

[0015]FIG. 1 is an oblique view of a coiled tubing rig reel using the level wind system of this invention in the process of level winding;

[0016]FIG. 2 shows a side profile view of the reel and the level wind system if FIG. 1 with the boom extended fully for controlling the outer wraps on the reel;

[0017]FIG. 3 illustrates a side view of the level wind system of FIG. 2, but with the boom retracted;

[0018]FIG. 4 is an oblique view of a partial longitudinal vertical cross-section of the level wind system of FIG. 3 showing the internals of the boom extension means

[0019]FIG. 5 shows an oblique view of the guide head with its rollers for contacting and urging the coiled tubing into the desired alignment;

[0020]FIG. 6 is a longitudinal vertical section through the middle of the boom of FIG. 3;

[0021]FIG. 7 shows an oblique view of an alternate guide head with rollers for contacting and urging the coiled tubing on all sides;

[0022]FIG. 8 shows a simple manually controlled hydraulic circuit for controlling the operation of the level winding of the coiled tubing; and

[0023]FIG. 9 shows an oblique view of an alternate guide head with rollers for contacting and urging the coiled tubing on all sides.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention provides an adaptation of a small hydraulic slewing crane having an extendable and elevatable boom configured to guide the coiled tubing of a coiled tubing service rig onto and off of a storage reel for deployment in a well. This guiding operation is termed level winding, since it involves laying the tubing in smooth, uniform layers on the reel so that the tubing is stored compactly, without overstress at the tubing crossings, and without risk of tubing binding during unreeling.

[0025] Referring now to the drawings, and initially to FIGS. 1 and 2, it is pointed out that like reference characters designate like or similar parts throughout the drawings. The Figures, or drawings, are not intended to be to scale. For example, purely for the sake of greater clarity in the drawings, wall thickness and spacing are not dimensioned as they actually exist in the assembled embodiment.

[0026]FIGS. 1 and 2 show the elements of the tubing storage assembly 10 of a coiled tubing rig in their relative operating positions, but without the mounting base or trailer and without the injector. The coiled tubing rig is not shown for the sake of clarity. The level wind mechanism of this invention is applicable to a variety of rig arrangements, such as those shown in Butler U.S. Pat. No. 5,937,943 or Andreychuk U.S. Pat. No. 6,003,598. The horizontal axis reel 11 holds a supply of continuous, reeled-up coiled tubing 12, the entering portion 13 of which is shown extending upwardly to an unshown injector assembly. Located in close proximity to the reel 11 on rig deck 14 is the level wind unit 15. Level wind unit 15 consists of a hydraulic slewing crane 16 supporting a roller guide head 80. The vertical pedestal 17 of crane 16 is positioned on the rig deck 14 and/or crossbeams of the rig foundation in the midplane between the vertical flanges of reel 11 and close enough to the reel periphery so that it can extend roller guide head 80 over the reel.

[0027] Pedestal 17, shown in FIG. 3, is a vertical hollow tube having a bottom transverse flange 18 suitable for welding or bolting to deck 14 and an upper gusseted transverse flange 19 which supports large diameter high moment capacity slewing bearing 22. Slewing bearing 22 shown in FIG. 4, which is annular and of ball or roller construction, is bolted on its outer race flange to flange 19 with bolts 23. The inner race flange of bearing 22 is bolted to slewing head 26.

[0028] Slewing head 26 consists of core tube 27, integral upper transverse flange 28, boom bracket 29, and elevating cylinder bracket 37. Core tube 27 extends downwardly a short distance below the level of rig deck 14. The inner race flange of slewing bearing 22 is bolted to the lower side of flange 28 to support slewing head 26 so that it can be pivoted about its vertical axis. Boom bracket 29 consists of two identical boom pin plates 30 which are welded perpendicular to the horizontal upper surface of flange 28 parallel and symmetrically spaced apart from the vertical axis of slewing head 26. A pin hole 32 extends through each boom pin plate 30 to support coaxial boom hinge pin 33. Transverse stiffener plate 34 is welded to both the boom pin plates 30 and the flange 28 to strengthen and rigidize boom bracket 29. Elevating cylinder bracket 37 consists of two identical parallel symmetrically spaced apart cylinder bracket plates 38 on the forward side of boom bracket 29. Cylinder bracket plates 38 are welded both to flange 28 and plate 34 and have elevating cylinder pin holes 39 for mounting coaxial first elevating cylinder pin 40.

[0029] At the lower end of core tube 27 of slewing head 26 is the rotator assembly 45. The rotator assembly consists of two horizontal parallel but opposed hydraulic cylinders 46 having mounting eyes both on the rod end and on the cylinder end. Each cylinder end eye is connected to the unshown rig frame at fixed cylinder axis 47 by a pin (unshown), while cylinder rod end pins 48 are mounted in the rod end eyes and thereby are connected to eccentric arms 49. Each of the two eccentric arms 49 is formed of a semicylindrical half collar having opposed projecting ears, which are in a vertical plane slightly offset to the half collar side from the vertical diametral plane. The inner diameter of the half collars is that of the core tube 27. One or more through holes in each ear permit clamping the eccentric arms to the lower end of core tube 27 of slewing head 26 with bolts 50 connecting the two eccentric arms 49. Radially projecting outwardly from each half collar is a horizontal plate welded to the half collar and having at its outward end a vertical axis pin hole through which the cylinder rod end pins 48 are engaged.

[0030] The boom assembly 55 is mounted to the boom bracket 29 of the slewing head 26. Boom assembly 55 consists of boom socket tube 56, boom middle tube 75, and boom inner tube 76. Boom socket tube 56 is a substantially rectangular steel tube having radiused edges between the flats of the tube and one end closed by a bolted-on end plate. Two identical reinforcing cheek plates having horizontal axis boom pivot eye holes 57 are symmetrically welded to the sides of the boom socket tube 56 near the closed end. Boom pivot eye holes 57 are located on the lower side of boom socket tube 56 and horizontal boom hinge pin 33 engaged with holes 57 connects the boom socket tube to slewing head 26. On the underside of boom socket tube 56 further outward from the location of boom pivot eye holes 57 in the direction away from the closed end of tube 56 is boom elevator bracket 58. Boom elevator bracket 58 consists of two identical parallel vertical plates having horizontal axis boom elevator bracket eye 59 through pin holes symmetrically welded to the bottom of tube 56. Hydraulic boom elevator cylinder 60 is connected through a horizontal eye on the back end of cylinder 60 to elevating cylinder bracket 37 by means of first elevating cylinder pin 40. Cylinder 60 is connected to boom elevator bracket 58 at its rod end by boom elevator cylinder rod end pin 61 which also passes through elevator bracket eye 59. Adjacent the closed end of boom socket tube 56 are horizontal axis extension cylinder mounting eyes 62 which penetrate concentrically through the vertical sides of tube 56. Boom extension cylinder 65 is mounted inside boom socket tube 56 by means of pinning boom extension cylinder rod end eye 66 to eyes 62 by means of boom extension cylinder rod end pivot pin 67. The cylinder end of boom extension cylinder 65 is fitted with horizontal boom extension cylinder outer end pivot eye 68 and inserted outer end pivot pin 69.

[0031] As shown in FIG. 6, boom middle tube 75 and boom inner tube 76 are also constructed of rectangular cross-section steel tubes similar to that used for boom socket tube 56. However, boom middle tube 75 is selected to be a close sliding fit to the interior of socket tube 56, and boom inner tube 76 is similarly chosen to be a close sliding fit to the interior of middle tube 75. The outer end of boom inner tube 76 has a transverse plate outer end mounting flange 77 welded onto the tube. Mounting flange 77, which has multiple drilled and tapped mounting holes in its face, does not project beyond the outer periphery of tube 76. Close to the outer end of inner tube 76 at midheight in the vertical tube walls are horizontal coaxial cylinder mount eyes which are engaged by boom extension cylinder outer end pivot pin 69 so that the boom extension cylinder 65 is thereby attached.

[0032] Roller guide head 80, shown in FIG. 5, projects outwardly from the outer end of boom inner tube 76. Roller guide head 80 consists of roller bracket 81 and a set of rollers 84 and 86 mounted thereto. Roller bracket 81 has back plate 82 which has two mirror image trapezoidal side plates 83 symmetrically spaced apart from the middle of back plate 81 and welded perpendicular to plate 82. Back plate 82 has multiple bolt holes in a pattern corresponding to that on the outer end mounting flange 77 of inner tube 76. The outer tip of each of trapezoidal side plates 83 has an inwardly projecting tab which is parallel to back plate 82 and has a central through hole normal to back plate 82. Drilled and tapped into back plate 82 and coaxial with the through hole in the tab of each side plate 83 are two side roller shaft mount holes. Identically offset from the back plate and parallel to it are two horizontal roller shaft mount holes near the comers of side plates 83 adjacent back plate 82. The horizontal roller shaft mount holes of one side plate 83 are tapped. Two horizontal axis rollers 84 and two side rollers 86 are each mounted to roller bracket 81 by a coaxial horizontal roller shaft 85 and side roller shaft 87, respectively. The roller shafts 85 and 87 have hex heads, long cylindrical shanks, and threaded tips which may be threadedly engaged in the tapped holes in roller bracket 81. Rollers 84 and 86 typically are provided with internal roller bearings at each end which are supported by shafts 85 and 87. The rollers 84 and 86 may be coated with rubber or other coatings which will distribute any load applied to the tubing passing over the rollers and thereby avoid permanently distorting the tubing. Roller bracket 81 is attached to outer end mounting flange 77 of inner tube 76 by multiple mounting bolts passing through the mounting bolt holes of back plate 82 and threadedly engaged in the tapped holes in the flange 77.

[0033] Referring to FIG. 8, the simple manually controlled hydraulic system 89 for manipulating the crane as a level winding mechanism is shown. Pump 90, typically a small piston pump, draws hydraulic fluid from tank 91. The output from pump 90 flows to a tee connection, where one leg supplies the control valves and cylinders and the other goes to a system relief valve 92. System relief valve 92 avoids dead-heading of the pump and the consequent damage. Boom elevator cylinder 60 is controlled by control valve 93 and the combination of check valve 94 and piloted relief valve 95. The combination of check valve 94 and piloted relief valve 95 are located on the piston side flow line of cylinder 60 to function as a cylinder lock valve to avoid release of the load due to external leaks or internal leaks in control valve 93. The piston side of boom elevator cylinder 60 is the side loaded by the weight and other vertical load components of the boom. Control valve 93 is a three-position, four-way, spring-centered, manually operated valve with the cylinder ports blocked and the pressure directed to tank 91 in the center position. Slewing cylinders 46 are run in parallel and are controlled by control valve 99, which is identical to control valve 93. Boom extension cylinder 65 is controlled by control valve 105 and the combination of check valve 106 and piloted relief 107. Valves 105, 106, and 107 are respectively identical to valves 93, 94, and 95 in construction and operation. The combination of check valve 106 and piloted relief valve 107 are located on the piston side flow line of cylinder 65 to function as a cylinder lock valve to avoid release of the load due to external leaks or internal leaks in control valve 105. The piston side of boom extension cylinder 65 is the side loaded by the weight and other axial load components of the boom.

[0034] Alternate roller guide head 200, shown in FIG. 7, is substantially the same as roller guide head 80, but with the addition of an additional outside roller for ensuring that the tubing cannot jump out of the guide head due to erratic reel or injector operation. Alternate roller guide head 200 projects outwardly from the outer end of boom inner tube 76. Alternate roller guide head 200 consists of roller bracket 201 and a set of rollers 204, 206, and 208 mounted thereto. Roller bracket 201 has back plate 202 which has two mirror image side plates 203 symmetrically spaced apart from the middle of back plate 201 and welded perpendicular to back plate 202. Back plate 202, which is identical to back plate 82 of roller guide head 80, has multiple bolt holes in a pattern corresponding to that on the outer end mounting flange 77 of inner tube 76. The side plates 203 are similar to those of roller guide head 80, but onto their basic trapezoidal profile on the outer side an ear is extended coplanar with the side plate and parallel to bottom plate 202. The outer tip of each of trapezoidal side plates 203 has an inwardly projecting tab which is parallel to back plate 202 and has a central through hole normal to back plate 202. Drilled and tapped into back plate 202 and coaxial with the through hole in the tab of each side plate 203 are two side roller shaft mount holes. Identically offset from the back plate and parallel to it are two horizontal roller shaft mount holes near the corners of side plates 203 adjacent back plate 202. The projecting coplanar ears near the outer end of side plates 203 have central horizontal axis holes for the mounting of a horizontal axis keeper roller. The horizontal roller shaft mount holes and the keeper roller shaft mount holes of one side plate 203 are tapped. Two horizontal axis rollers 204, two side rollers 206, and outside keeper roller 208 are each mounted to roller bracket 201 by a coaxial horizontal roller shaft. Horizontal roller shafts 205 are used for both horizontal rollers 204 and outside keeper roller 208, while side roller shafts 207 are used for side rollers 206. The roller shafts 205 and 207 have hex heads, long cylindrical shanks, and threaded tips which may be threadedly engaged in the tapped holes in roller bracket 201. Rollers 204, 206, and 208 typically are provided with internal roller bearings at each end which are supported by shafts 205 and 207. The rollers 204, 206, and 208 may be coated with rubber or other coatings which will distribute any load applied to the tubing passing over the rollers and thereby avoid permanently distorting the tubing. Roller bracket 201 is attached to outer end mounting flange 77 of inner tube 76 by multiple mounting bolts 88 passing through the mounting bolt holes of back plate 82 and threadedly engaged in the tapped holes in the flange 77.

[0035]FIG. 9 shows a second alternative roller guide 300, which may be used in place of either roller guide 80 or 200. Roller guide head 300 consists of a frame 302, which is made by bending a rectangular steel plate into a symmetrical vee with an included angle of approximately 90° to 135°. Frame 302 is mounted symmetrically on the outer end of the boom inner tube 303. Boom inner tube 303 is similar to boom inner tube 76, but does not have the transverse flange at its outer end. First roller 305a has interior roller bearings corresponding to those of the rollers in the other embodiments and is mounted by first roller pedestal 306 and second roller pedestal 307, which are supported on frame 302. Shaft 308 is supported in pedestals 306 and 307 and serves to mount roller 305 a. First roller 305 a is parallel to one interior side of the vee of frame 302, while second roller 305 b is similarly supported by its respective first and second roller pedestals 306 and 307 and shaft 308, but second roller 305 b is mounted on the other interior face of the vee. Keeper roller 312 is constructed similarly to rollers 305 a,b, but is typically slightly longer than rollers 305 a,b. Keeper roller 312 is mounted at the outer tips of the vee by its roller pedestals 306 and a keeper roller shaft 313. The roller configuration of the roller guide embodiment 300 thus forms a triangular guide for tubing 301 passing through the roller guide.

[0036] Operation of the Invention:

[0037] The operation of this invention is described herein for the reeling in of the coiled tubing when the level winding is critical. Level winding is less critical for unreeling and in some cases may be avoided for unreeling.

[0038] The crane 16 is rotated about its vertical axis in the center of its pedestal 17 in the following manner. The slewing control valve 99 for the rotator cylinders 46 is shifted so that, for rotation which is counterclockwise when viewed downwardly, hydraulic fluid from pump 90 is applied to the piston side of the cylinders, causing the rod to extend and fluid from the rod end to return to tank 91 through the return port of valve 99. For clockwise motion, the control valve 99 is shifted so that fluid is applied to the rod side of the cylinders, causing the rod to retract and fluid from the piston end of cylinders 46 to return to tank 91 through the return port of valve 99. The forces and motion applied to the rod are reacted against by the rig structure through the pins joining cylinders 46 to the rig structure at fixed cylinder axes 47. The rod force is transferred to the eccentric arms 49 through the cylinder rod end pins 48 and thence to the lower end of the core tube 27 of slewing head 26 by means of friction induced between the half collars of the eccentric arms and the core tube by the clamping action of clamp bolts 50. Since the rod forces acting on core tube 27 are of equal magnitude but opposite direction and are eccentric from the vertical axis of the crane 16, a pure force couple is induced on core tube 27 and the boom assembly 55. A minor portion of this couple will be expended to overcome friction and to overcome inertia if moving. However, most of this couple will result in lateral forces being applied to the coiled tubing 13 by one of the side rollers 86 of the roller guide head 80. These lateral forces provide the primary guidance for ensuring that the tubing is laid in uniformly on the reel during rewinding.

[0039] The boom assembly 55 of crane 16, which is pivoted about boom hinge pin 33 mounted in the boom mounting pin hole of slewing head 26 and engaged in boom pivot eye 57 of the boom socket tube 56, is caused to raise or lower in the following manner. The boom elevation control valve 93 for the boom elevator cylinder 60 is shifted to cause fluid from pump 90 to be applied to the piston side of the cylinder to extend the rod and raise the boom. The static cylinder end of boom elevator cylinder 60 reacts on the elevating cylinder bracket 37 through first elevating cylinder pin 40 while the rod end of the cylinder reacts on boom elevator bracket 58 of boom socket tube 56 of boom assembly 55 through boom elevator cylinder rod end pin 64. The weight of boom assembly 55 and any loads applied to the horizontal axis rollers 84 of roller guide head 80 by the tubing 13 are reacted against by the boom elevator cylinder 60 and the boom hinge pin 33. By raising the boom sufficiently, the horizontal rollers 84 can exert a normal force on the tubing causing it to be lifted, if necessary.

[0040] The boom assembly 55 can be extended or retracted in the following manner. The boom extension control valve 105 is shifted to cause hydraulic fluid from pump 90 to be applied to the piston side of the boom extension cylinder 65 to extend the boom. As this is happening, the fluid from the rod side of cylinder 65 is returned to tank 91 through the return ports of valve 105. The fluid entering the piston end of cylinder 65 freely passes through check valve 106. To retract the boom, the boom extension control valve is shifted to cause fluid from pump 90 to be applied to the rod side of the cylinder 65 to cause the rod to retract and retract the boom. The fluid on the piston side of cylinder 65 is permitted to outflow from the cylinder when the pressure applied to the rod side of the cylinder. The pilot operated relief valve 107 opens so that the return flow can pass to tank 91 through the return port of valve 105. The rod end of the boom extension cylinder 65 reacts against boom extension cylinder mounting 62 of boom socket tube 56 through boom extension cylinder rod end pivot pin 67 and boom cylinder rod end eye 66. The cylinder end of boom extension cylinder 65 reacts against the boom inner tube 76 through boom extension cylinder outer end pivot pin 69 engaged in cylinder mount eyes of boom inner tube 76 and boom extension cylinder outer end pivot eye 68. The loads on the boom extension cylinder are primarily friction and the axial component of the weight vector, but in some cases, tubing 13 reactions on the horizontal axis rollers 84 also impact the cylinder loads.

[0041] The following description describes the operation of the level winder during rewinding. If the tubing 13 is not already fed through the roller guide head 80, then that is done after the roller guide head 80 or 200 is aligned with the desired starting position of the tubing on the reel 11. Alternate roller guide head 200 functions identically to roller guide head 80, but the outside keeper roller 208 is only mounted after the tubing 13 is positioned between the other rollers. The keeper roller functions to ensure that tubing 13 cannot disengage from the roller guide head. Alignment of the roller guide head 80 or 200 involves the following steps. First, the boom assembly 55 is elevated sufficiently to ensure clearance above the reel and then the boom is extended outwardly to locate it properly above and ahead of the winding surface of the current tubing layer. The boom and roller guide head must always be clear of the flanges of reel 11. Some care is necessary, since the bending strength in the tubing and the residual bending stresses resulting from its passage through the overbend between the wellhead and the reel cause the tubing to follow a curved path, even under tension. As the reel 11 is rotated, drawing tubing 13 onto its drum surface or the surface of the tubing 12 which is already spooled, the boom assembly 55 is continuously slewed with a slight lag to cause a side roller 86 to bear on the tubing 13 near the touchdown point on the reel. This force applied by the side roller and controlled by the slewing of the boom in turn causes tubing 13 to bear against the last turn laid on the reel. When a side flange of the reel 11 is reached, it is necessary for the slewing action to be halted until the tubing 13 climbs on top of the previous layer, thereby beginning a new layer. After the first tubing wrap on the new layer is complete, the slewing is reversed in direction and, slightly lagging to ensure tight packing of the wraps in the layer, proceeds toward the opposite flange. In general, it is advisable to avoid exerting much force or to exert no force on the tubing 13 with the horizontal axis rollers 84, as this lateral force could excessively work the tubing and thereby shorten its fatigue life. Similarly, if alternate roller guide head 200 is used, the outside keeper roller should only contact the tubing in the event of the tubing trying to lift out of the roller guide head.

[0042] The control of the three hydraulic valves operating the crane 16 readily can be done manually, or the controls could be computerized with proportional solenoid valves replacing control valves 93, 99, and 105 and with a prerecorded pattern for each tubing size. In order to properly spool the tubing automatically, at a minimum a footage sensor and/or a reel turn count sensor would be required. Roller load sensors might also be required. Typically, any automatic control system would be provided with manual overrides. Generally, the slewing adjustments are made much more than those for boom extension or boom elevation.

[0043] The advantages of this invention accrue from the inexpensive, reliable construction of the crane and its simple, insensitive manual control. If automatic control is desired, it too can be made relatively simple and inexpensive. The maintenance of the crane is simple, inexpensive, and uses commonly available parts. An additional advantage of this invention is that the crane also may be utilized for lifting purposes by either replacing the roller guide head or providing separate lifting means with a permanently mounted roller guide head.

[0044] As will be understood readily by those skilled in the art, various changes in the configuration of this invention can be made without departing from the spirit of the invention. For example, a single cylinder could slew the boom using a chain with idler sprockets and a double-ended cylinder. Similarly, a hydraulic motor could be used to slew the crane. Likewise, other ways of extending or elevating the boom could be utilized, as will be recognized easily by those skilled in the art. These modifications do not constitute a departure from the spirit of this invention. 

What is claimed is:
 1. A level winding rotationally mounted and axially extensible knuckle boom for use with a coiled tubing injector, the knuckle boom comprising: (a) slewing means for controllably slewing the boom about a vertical axis; (b) elevating means for controllably elevating and lowering the boom; (c) extension means for controllably extending and retracting the boom; and (d) guide roller means for guiding a tubing during the tubing winding or unwinding onto or off of a storage reel, said guide roller means mounted on an outer end of said boom; whereby the boom is selectably controlled so that the tubing alignment is controlled by the roller guide means as the tubing is wound or unwound onto or off of the storage reel.
 2. The boom of claim 1, wherein the slewing means includes a rotationally supported base mounted to the boom and attached to a fixedly mounted rotator assembly.
 3. The boom of claim 2, wherein the rotator assembly comprises two horizontal, parallel and opposed hydraulic cylinders whereby the rotationally supported base is rotated by the coordinated action of the hydraulic cylinders thereby causing the boom to rotate.
 4. The boom of claim 1, wherein the elevating means includes a hydraulic cylinder.
 5. The level winding system of claim 1, wherein the guide roller means comprises a roller bracket, a pair of spaced apart parallel horizontal rollers and a pair of spaced apart parallel orthogonal rollers, wherein the horizontal rollers are mounted on opposed sides of the roller bracket and the pair of orthogonal rollers are mounted on the roller bracket between the horizontal rollers in a plane that is substantially perpendicular to the horizontal roller axes.
 6. The level winding system of claim 5, wherein each horizontal and orthogonal roller is mounted to the roller bracket on a shaft and rotates about a plurality of internal roller bearings.
 7. The level winding system of claim 5, wherein the horizontal and orthogonal rollers have a surface coating to assist in distributing a load applied to the tubing passing over the rollers.
 8. A level winding system for use with a coiled tubing injector unit comprising: (a) a tubing storage reel; (b) a crane having a boom, said crane comprising: a rotating element for controllably rotating the boom about a vertical axis, a hydraulic cylinder for controllably elevating and lowering the boom, and an extension element for controllably extending and retracting the boom; and (c) a guide roller element for guiding a tubing during the tubing winding or unwinding onto or off of the tubing storage reel, said guide roller element mounted on an outer end of said boom and comprising a roller bracket, a horizontal roller and an opposed pair of substantially parallel orthogonal rollers, wherein the axes of the orthogonal rollers are substantially perpendicular to the axis of the horizontal roller; whereby the roller guide element is positioned by the crane and the boom as the roller guide element guides the tubing onto or off of the storage reel.
 9. The level winding system of claim 8, wherein the crane is hydraulically operated.
 10. The level winding system of claim 8, wherein the rotating element includes a rotationally supported base mounted to the boom at one end and attached to a fixedly mounted rotator assembly at a second end.
 11. The level winding system of claim 10, wherein the rotator assembly comprises two horizontal, parallel and opposed hydraulic cylinders whereby the boom is rotated by the coordinated action of the hydraulic cylinders causing the supported base to rotate.
 12. The level winding system of claim 8, wherein the horizontal and orthogonal rollers are mounted to the roller bracket on a shaft and rotate about a plurality of internal roller bearing.
 13. The level winding system of claim 8, wherein the horizontal and orthogonal rollers have a surface coating to assist in distributing any load applied to the tubing passing over the rollers.
 14. The level winding system of claim 8, further comprising a controlling mechanism for selectable positioning the roller guide element.
 15. The level winding system of claim 8, wherein the controlling mechanism of the level winding system is controlled with a programmable device having a manual override mechanism.
 16. A level winding system comprising: (a) a reel holding a coiled tubing, said tubing wound and unwound from the reel by the level winding system; (b) a roller guide head proximal to the reel and comprising multiple rollers, said rollers partially or fully surround the tubing to partially constrain the lateral movement of the tubing; and (c) roller guide head manipulation element comprising a crane, a plurality of crane actuators and a crane control device.
 17. The level winding system of claim 16, wherein said crane comprises: (a) a structural base mounting a pedestal; (b) a slewing bearing at an upper end of the structural base; (c) a slewing head rotatable about the vertical axis of the pedestal on said slewing bearing and supporting a trunnion having a horizontal axis; and (d) an elevatable telescopic boom supported at a first end by a shaft positioned in the trunnion of the slewing head and attached to the roller guide head at a second end; whereby selectable operation of the crane rotates, extends or elevates the boom.
 18. The level winding system of claim 16, wherein the crane actuators are hydraulically operated.
 19. The level winding system of claim 16, wherein the multiple rollers comprise a pair of spaced apart parallel horizontal rollers and a pair of spaced apart parallel orthogonal rollers, the horizontal rollers are mounted on opposed sides of a roller bracket and the pair of orthogonal rollers are mounted on the roller bracket between the horizontal rollers in a plane that is substantially perpendicular to the horizontal roller axes.
 20. The level winding system of claim 16, wherein the horizontal and orthogonal rollers are mounted to the roller bracket on a shaft and rotate about a plurality of internal roller bearing.
 21. The level winding system of claim 16, wherein the crane control device is programmable with a manual override mechanism. 